The molecular mechanism of the action of cholinergic and alpha-adrenergic agonists will be investigated in the rat parotid. It has been demonstrated that alpha-adrenergic or cholinergic stimulation cause an increased incorporation of 32 Pi into phosphatidylinositol (PI) in the rough endoplasmic reticulum in the rat parotid (phospholipid effect). Michell and co-workers have shown that this is preceded by massive breakdown of PI. Since both effects do not require exogenous Ca ions, they seem to directly connected with the activation of either receptor. The subcellular localization of the breakdown of Pi will be studied. The methods to be employed are: subcellular fractionatton and phospholipid extraction and separation by chromatography of deacylated phoshpholipids. The in vitro breakdown of PI in membrane from control tissue and tissue previously exposed to alpha-adrenergic and cholinergic agents will be studied. The breakdown of PI in membranes from control tissue and tissue previously exposed to alpha-adrenergic and cholinergic agents will be studied. The breakdown of Pi will be monitored by the appearance of 3H-inositol released from membranes prelabelled with 3H-inositol. It has been shown that alpha-adrenergic and cholinergic stimulation inhibit cAMP production caused by betw-adrenergic agonists. The cholinergic effect did not require exogenous Ca ions, implying that the inhibition is more directly connected with the activation of the cholinergic receptor, and not secondary to Ca ions influx mediated by this receptor. The influence of cholinergic and alpha-adrenergic stimulation on the activities of adenylate cyclase and cAMP phosphodiesterase will be studied both by adding agonists to tissue cell-free preparations and after previous exposure of tissue slices to agonists prior to homogenization or membrane isolation. The methods to be used are conventional adenylate cyclase or cAMP phosphodiesterase assays.